Reflectivity and conductivity of YBa2Cu3O7

We obtain the a-b plane infrared conductivity of YBa2Cu3O7 from temperature-dependent reflectivity spectra of crystals and films with Tc92 K. The normal state is characterized by a free-carrier band with an enhanced low-frequency mass and a frequency-dependent scattering rate, which indicate coupling to an excitation spectrum with a characteristic frequency scale of c700 cm-1 and coupling strength of 2 to 3. © 1989 The American Physical Society.